Ldr sensor is a special resistor made of semiconductor materials such as sulfide or selenide barrier. It is also coated with moisture-proof resin and has photoconductive effect.
Ldr sensor is very sensitive to light. The stronger the light, the lower the resistance. With the increase of illumination intensity, the resistance value decreases rapidly, which can be reduced to less than 1KΩ.
The working principle of ldr photoresistor is based on the internal photoelectric effect, that is, the semiconductor photosensitive material is encapsulated in the shell with transparent window by installing electrode leads at both ends to form an ldr sensor. In order to increase sensitivity, the two electrodes are usually in the comb shape.
1. The ldr photocell module is most sensitive to the ambient light intensity, which is generally used to detect the ambient brightness and intensity.
2. When the module has no light condition or the light intensity can not reach the set threshold, the DO port output is in the high level. When the light intensit of the external environment exceeds the set threshold, module D0 output is in the low level.
3. The output D0 of the small board digital quantity can be directly connected with the single chip computer. The high and low levels can be detected by the single chip computer so as to detect changes in light intensity in the environment.
4. AO output of small board analog can be connected with AD module. Through AD conversion, more accurate numerical value of the ambient light intensity can be obtained.